Efficient Network Data Transfer

1. A computer-implemented method for providing data access services relative to otherwise non-accessible storage subsystems, comprising: a first database server executing first query language statements that request access to first schema objects defined in a query language, wherein data for said first schema objects are stored in first non-schema objects in a first persistent storage subsystem, wherein said first database server executing said first query language statements includes using a first set of access primitives to access natively said first non-schema objects in said first persistent storage subsystem, and wherein said first set of access primitives provides direct access to said first non-schema objects; said first database server providing, to a second database server that is remote from said first database server, said first set of access primitives, wherein said second database server cannot access said data for said first schema objects stored in said first non-schema objects in said first persistent storage subsystem without said first database server retrieving and transmitting said data for said first schema objects to said second database server; said first database server receiving, from said second database server, at least one access primitive, in said first set of access primitives, in a message that requests access to at least one of said first non-schema objects; in response to receiving said at least one access primitive in said message, said first database server executing said at least one access primitive to access said at least one of said first non-schema objects in said first persistent storage subsystem and providing said at least one of said first non-schema objects as data for at least one of said first schema objects to said second database server; wherein the computer-implemented method is performed by one or more computing devices.

2. The method of claim 1 , wherein said first database server provides, to a first database client that is associated with said first database server, a first set of database services including accessing said first persistent storage subsystem, wherein said first set of access primitives is used by said second database server to provide, to a second database client that is associated with said second database server, a second set of database services including accessing said first persistent storage subsystem, and wherein said second set of database services is identical to said first set of database services.

3. The method of claim 1 , further comprising: said second database server executing second query language statements that request access to second schema objects defined in a query language, wherein data for said second schema objects are stored in second non-schema objects in a second persistent storage subsystem, wherein said second database server executing said second query language statements includes using a second set of access primitives to access natively said second non-schema objects in said second persistent storage subsystem, and wherein said second set of access primitives provides direct access to said second non-schema objects; said second database server providing, to said first database server, said second set of access primitives, wherein said first database server cannot access said data for said second schema objects stored in said second non-schema objects in said second persistent storage subsystem without said second database server retrieving and transmitting said data for said second schema objects to said first database server; said second database server receiving, from said first database server, at least one second access primitive, in said second set of access primitives, in a second message that requests access to at least one of said second non-schema objects; in response to receiving said at least one second access primitive in said second message, said second database server executing said at least one second access primitive to access said at least one of said second non-schema objects in said second persistent storage subsystem and providing said at least one of said second non-schema objects as data for at least one of said second schema objects to said first database server.

4. The method of claim 3 , wherein said first set of access primitive is identical to said second set of access primitives.

5. The method of claim 3 , wherein the first database server provides, to a first database client that is associated with the first database server, a first set of database services including accessing the first persistent storage subsystem, wherein the first set of access primitives is used by the second database server to provide, to a second database client that is associated with the second database server, a second set of database services including accessing the first persistent storage subsystem, and wherein the first set of database services is identical to the second set of database services in terms of application programming interface.

6. The method of claim 1 , wherein said first persistent storage subsystem is a network storage subsystem that does not have any network link with said second database server.

7. The method of claim 1 , wherein said first non-schema object is a data block in said first persistent storage subsystem.

8. The method of claim 1 , wherein said first persistent storage subsystem is a network storage subsystem that does not have any network link with said second database server.

9. The method of claim 1 , further comprising: said second database server using one or more access primitives in said first set of access primitives to retrieve one or more first data blocks in said first persistent storage system from said first database server; and said second database server repairing one or more second data blocks in a second persistent storage system accessible to said second database server.

10. The method of claim 1 , wherein said first database server communicates with said second database server through a message pipe.

11. The method of claim 1 , wherein said data for said at least one first schema object is encrypted while being transported through a message pipe between said first database server and said second database server.

12. A computer-readable storage media storing one or more sequences of instructions which, when executed by one or more processors, causes the one or more processors to perform: a first database server executing first query language statements that request access to first schema objects defined in a query language, wherein data for said first schema objects are stored in first non-schema objects in a first persistent storage subsystem, wherein said first database server executing said first query language statements includes using a first set of access primitives to access natively said first non-schema objects in said first persistent storage subsystem, and wherein said first set of access primitives provides direct access to said first non-schema objects; said first database server providing, to a second database server that is remote from said first database server, said first set of access primitives, wherein said second database server cannot access said data for said first schema objects stored in said first non-schema objects in said first persistent storage subsystem without said first database server retrieving and transmitting said data for said first schema objects to said second database server; said first database server receiving, from said second database server, at least one access primitive, in said first set of access primitives, in a message that requests access to at least one of said first non-schema objects; in response to receiving said at least one access primitive in said message, said first database server executing said at least one access primitive to access said at least one of said first non-schema objects in said first persistent storage subsystem and providing said at least one of said first non-schema objects as data for at least one of said first schema objects to said second database server.

13. The medium of claim 12 , wherein said first database server provides, to a first database client that is associated with said first database server, a first set of database services including accessing said first persistent storage subsystem, wherein said first set of access primitives is used by said second database server to provide, to a second database client that is associated with said second database server, a second set of database services including accessing said first persistent storage subsystem, and wherein said second set of database services is identical to said first set of database services.

14. The medium of claim 12 , wherein said one or more sequences of instructions further comprise instructions which, when executed by one or more processors, causes the one or more processors to perform: said second database server executing second query language statements that request access to second schema objects defined in a query language, wherein data for said second schema objects are stored in second non-schema objects in a second persistent storage subsystem, wherein said second database server executing said second query language statements includes using a second set of access primitives to access natively said second non-schema objects in said second persistent storage subsystem, and wherein said second set of access primitives provides direct access to said second non-schema objects is enabled by said second set of access primitives; said second database server providing, to said first database server, said second set of access primitives, wherein said first database server cannot access said data for said second schema objects stored in said second non-schema objects in said second persistent storage subsystem without said second database server retrieving and transmitting said data for said second schema objects to said first database server; said second database server receiving, from said first database server, at least one second access primitive, in said second set of access primitives, in a second message that requests access to at least one of said second non-schema objects; in response to receiving said at least one second access primitive in said second message, said second database server executing said at least one second access primitive to access said at least one of said second non-schema objects in said second persistent storage subsystem and providing said at least one of said second non-schema objects as data for at least one of said second schema objects to said first database server.

15. The medium of claim 14 , wherein said first set of access primitive is identical to said second set of access primitives.

16. The medium of claim 14 , wherein the first database server provides, to a first database client that is associated with the first database server, a first set of database services including accessing the first persistent storage subsystem, wherein the first set of access primitives is used by the second database server to provide, to a second database client that is associated with the second database server, a second set of database services including accessing the first persistent storage subsystem, and wherein the first set of database services is identical to the second set of database services in terms of application programming interface.

17. The medium of claim 12 , wherein said first persistent storage subsystem is a network storage subsystem that does not have any network link with said second database server.

18. The medium of claim 12 , wherein said first non-schema object is a data block in said first persistent storage subsystem.

19. The medium of claim 12 , wherein said first persistent storage subsystem is a network storage subsystem that does not have any network link with said second database server.

20. The medium of claim 12 , wherein said one or more sequences of instructions further comprise instructions which, when executed by one or more processors, causes the one or more processors to perform: said second database server using one or more access primitives in said first set of access primitives to retrieve one or more first data blocks in said first persistent storage system from said first database server; and said second database server repairing one or more second data blocks in a second persistent storage system accessible to said second database server.

21. The medium of claim 12 , wherein said first database server communicates with said second database server through a message pipe.

22. The medium of claim 12 , wherein said data for said at least one first schema object is encrypted while being transported through a message pipe between said first database server and said second database server.